Swaging die

ABSTRACT

The die is used to produce cylindrical stock in a swaging machine which comprises only two hammers adapted to blow one against the other and in which a workpiece is rotated about its axis and axially fed between said hammers at the same time. Each of said hammers carries one of said dies for engaging said workpiece. The die is formed with a groove having the configuration of an obtuse-angled V. The groove has first and second side faces, which respectively form first and second working surfaces engageable with said workpiece. The groove has a prismatic finishing portion and an entrance portion which axially precedes and tapers in the shape of a wedge to said finishing portion. A plane which bisects the angle between said first and second working surfaces in said finishing portion includes in said entrance portion a larger angle with said first working surface than with said second working surface. Each die is mounted on its hammer in such a manner that the groove extends along the axis of the workpiece, the first working surface is the leading working surface relative to the rotating workpiece, the second working surface is the trailing working surface relative to the rotating workpiece, and said plane extends through the axis of the workpiece.

practice that the cavity be substantially filled with liq uid lubricant in order to insure that the forced lubrication takes place as early in the draw as possible.

It is fully within the scope of this invention to provide a suitable arrangement for containing the liquid forced out of the die cavity, and returning it to the cavity as the punch and part are withdrawn. By way of example, a sheet metal dike can easily be provided surrounding the hold-down. When the punch and part are withdrawn from the die cavity, substantially all of the liquid will be returned to the cavity.

It is believed that the foregoing constitutes a full and complete disclosure of this invention, and no limitations are intended except insofar as set forth in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a method of deep drawing metallic articles from sheet material including the steps of providing a die having a top surface and a female cavity terminating at said top surface in a die radius, placing a sheet of material over said cavity, holding said sheet of material against said die top surface whereby to restrict wrinkling of said sheet during drawing, and drawing said sheet of material into said cavity with a male die punch: the improvement comprising the steps of substantially filling said cavity with a liquid lubricant prior to drawing and continuously forcing liquid lubricant out of said cavity during drawing, all liquid lubricant forced out of said cavity being forced between said material being drawn and said die radius and die top surface in a direction opposite to the flow of said material being drawn.

2. The method claimed in claim 1 wherein said liquid lubricant is forced out of said cavity by the entrance therein of said punch and said material being drawn.

3. The method claimed in claim 1 wherein said liquid lubricant is water.

4. The method claimed in claim 2 wherein said liquid lubricant is water.

5. The method claimed in claim 4 wherein said water contains a small quantity of water soluble lubricant.

SWAGING DIE This invention relates to a swaging die for producing cylindrical stock in swaging machines which comprise only two hammers blowing one against the other, in which die the working surfaces are formed by the side faces of a groove which has the configuration of an obtuse-angled V and extends in the direction of travel of the workpiece, which is rotated about its axis, said groove having an entrance portion which tapers in the shape of a wedge to a prismatic finishing portion.

To make cylindrical stock, such as cylindrical bars or shafts provided with collars and conical portions, it is conventional to use swaging machines which comprise four hammers which extend radially to the workpiece and are angularly spaced 90 apart and carry dies which surround the workpiece. The use of this machine results in a rapid and comparatively exact operation, which involves only a low labor cost. If the workpieces are large in diameter, however, swaging machines comprising four hammers would necessarily have large dimensions and would involve a high capital expenditure. For this reason swaging machines comprising only two hammers which blow one against the other are often preferred for shaping workpieces which are large in cross-section. Whereas the output of such machine is lower, they cost much less than swaging machines which comprise four hammers.

ln swaging machines comprising only two hammers which blow one against the other, a manipulator is used to rotate the workpiece about its own axis and to feed the workpiece in its axial direction between the hammers. So far, the V-shaped groove which is formed in the die and has side faces serving as working faces is shaped in its entrance portion and in its finishing portion to be symmetrical to the plane which extends through the vertex of the groove and the axis of the workpiece so that the angles between that plane and the working surfaces formed by the side faces are equal. As a result, the main deformation is effected only at that working surface which is the leading surface relative to the rotating workpiece, i.e., at that working surface which is engaged first by the rotating workpiece, whereas almost no deformation can be observed at the other working surface. As a result, the deformation is entirely unsymmetrical with respect to the plane which extends through the vertex of the groove and the axis of the workpiece so that the core of the workpiece is weakened and the workpiece is not uniformly worked throughout its cross-section and assumes a curved shape unless it is adequately guided.

It is an object of the invention to eliminate this disadvantage and so to improve the die which has been described first hereinbefore that both working surfaces contribute approximately to the same extent to the deformation so that the workpiece is thoroughly worked through and a weakening of the core is avoided.

This object is accomplished according to the invention in that in the entrance portion the angle included by the working surface which is the leading surface rel ative to the rotating workpiece and the plane extending through the vertex of the groove and the axis of the workpiece is larger than the angle between the latter plane and the trailing working surface whereas the two angles are equal in the finishing portion, in known manner. As a result, the leading working surface, which is first engaged by the rotating workpiece, is somewhat set back in the direction of rotation whereas the trailing surface disposed on the outlet side is correspondingly advanced so that the deformation, specifically the critical deformation in the entrance portion, where the main reduction in diameter is effected, is shared by both working surfaces. The resultant of the shaping forces at the two working surfaces thus extends approximately through the axis of the workpiece and the workpiece is well and uniformly worked through and remains straight during the swaging operation even without special guide means. For the finishing of the workpiece, the working surfaces include equal angles with the plane which extends through the vertex of the groove and the axis of the workpiece.

The difference between the two angles will depend on the feeding speed of the workpiece, the speed of the workpiece and the included angle of the V-shaped die groove and may amount, e.g., to 3-4.

An embodiment of the invention is shown diagrammatically and by way of example on the accompanying drawing, in which FIG. 1 is a sectional view taken through the axis of the workpiece and shows the dies secured to the two hammers blowing one against the other and FIGS. 2 and 3 are transverse sectional views taken on lines II-II and III-III, respectively, in FIG. 1 and showing also the workpiece to be shaped.

The swaging machine, not shown, comprises two hammers, which blow one against the other and to which the workpiece is axially fed while being rotated about its axis. Identical swaging dies 1 are secured to the two hammers at their end faces. The working surfaces of the dies 1 consistof the side faces of a groove which extends in the direction of travel of the workpiece and has the configuration of an obtuse-angled V. That groove comprises an entrance portion 4, which tapers in the shape of a wedge to a prismatic finishing portion 3, and an exit portion 5, which is symmetrical to the entrance portion. The exit portion 5 serves as an inlet portion when the feeding direction is reversed for a so-called back-swaging operation.

In accordance with FIG. 2, the angle a included by the working surface 7, which is the leading working surface relative to the rotating workpiece,and the plane E extending through the vertex of the groove and the axis of the workpiece 6 is in the entrance portion larger by about 3-4 than the angle B between the plane E and the trailing working surface 8. The total angle a [3 is approximately The two angles a, B in the finishing portion are approximately equal.

What is claimed is:

l. A swaging die for producing cylindrical stock in a swaging machine which comprises only two hammers adapted to blow one against the other and in which a workpiece is rotated about its axis and axially fed between said hammers at the same time, each of said hammers carrying one of said dies for engaging said workpiece,

said die being formed with a groove having the configuration of an obtuse-angled V,

said groove having first and second side faces, which respectively form first and second working surfaces engageable with said workpiece,

said groove having a prismatic finishing portion and an entrance portion which axially precedes and tapers in the shape of a wedge to said finishing portion,

a plane which bisects the angle between said first and second working surfaces in said finishing portion including in said entrance portion a larger angle with said first working surface than with said second working surface. 

1. A swaging die for producing cylindrical stock in a swaging machine which comprises only two hammers adapted to blow one againsT the other and in which a workpiece is rotated about its axis and axially fed between said hammers at the same time, each of said hammers carrying one of said dies for engaging said workpiece, said die being formed with a groove having the configuration of an obtuse-angled V, said groove having first and second side faces, which respectively form first and second working surfaces engageable with said workpiece, said groove having a prismatic finishing portion and an entrance portion which axially precedes and tapers in the shape of a wedge to said finishing portion, a plane which bisects the angle between said first and second working surfaces in said finishing portion including in said entrance portion a larger angle with said first working surface than with said second working surface. 